Author Topic: my henry abe pistons and cyls compression Q (Read 5306 times)

BPellerine · « **on:** October 12, 2015, 04:19:19 PM »

a pic of my ha pistons and the package they came in,appear to be diff than the other types of ha pistons

the cylinders are early with nice thick fins and no casting flash!

Bill/BentON Racing · « **Reply #1 on:** October 12, 2015, 05:04:33 PM »

I've got 3 of those!! That's what was in Purple Rain! !

, Bill Nice looking cylinder.

BPellerine · « **Reply #2 on:** October 12, 2015, 05:18:59 PM »

hmm I did not know that was what was in purple rain,I am gathering henry abe stuff so I have spares,this going in my engine.bill

NalleyRacing · « **Reply #3 on:** October 12, 2015, 09:44:48 PM »

I have 3 used henry abe pistons from a build right now along with a NOS set of sleeves with the taper at the bottom.
Funny thing is the old ones are flat top turbo style pistons like you have there and we found in purple rain.. but my new Henry Abe set have slightly more compression

PeWe · « **Reply #4 on:** October 13, 2015, 04:52:55 AM »

Look same as mine... http://forums.sohc4.net/index.php/topic,150456.msg1717063.html#msg1717063
Bill, diameter of your pistons?

Mine are like 67.45mm around the sleeves, 66.9mm at top.
My cylinder to them is old, before the additional 8 thick o-rings to seal better. Will it leak more without these?

BPellerine · « **Reply #5 on:** October 13, 2015, 10:45:03 AM »

pewe they are all 67 mm pistons for the ha kit,so maybe a little diff in tolerance ,the cyls are bored for each piston.I don't think that they will leak any more than later cyls,cycle x say you don't have to use the seals with their mls gasket,and what did people do before the 8 seals?billp

BPellerine · « **Reply #6 on:** October 13, 2015, 10:54:26 AM »

Quote from: TreyAllen on October 12, 2015, 09:44:48 PM

I have 3 used henry abe pistons from a build right now along with a NOS set of sleeves with the taper at the bottom.
Funny thing is the old ones are flat top turbo style pistons like you have there and we found in purple rain.. but my new Henry Abe set have slightly more compression

these have a slight dome that you cant see,how about a pic of the diff pistons so they are in one place,slipper type,pewes type,and these.I thought there were only 2 types.bill

Jerry Rxman Griffin aka MuthaF'er · « **Reply #7 on:** October 13, 2015, 11:33:01 AM »

My take is if the cylinders were made for the seals then use them.

As you say, there are 2 different HA 900 pistons. Maybe more?? I've only seen/noticed 2 types. You have the heavier ones.

Bill/BentON Racing · « **Reply #8 on:** October 13, 2015, 03:38:19 PM »

Well, not so so fast young man, you thinking with the little head anyhoo!

I personally don't use them like Kenny / CycleX, I could be wrong, let MikeR. chime in, but I believe he's no fan either, Bill

Jerry Rxman Griffin aka MuthaF'er · « **Reply #9 on:** October 13, 2015, 04:37:10 PM »

you damn straight bro!

I figure it's extra insurance as my rationale. The 1000 I just put together had the cylinders done by Big Jay @ APE. Later model cylinders. He plugged up those holes for the seals so he doesn't believe in them either. Said they are unnecessary so I CAN'T use them on this engine.

BPellerine · « **Reply #10 on:** October 13, 2015, 05:34:07 PM »

I am not saying to use/not use the seals,and I know why they are there but lots of early bikes do not have them and with prep they should be as good as any,if you get a gasket set now for 69/78 the head gasket is made for the seals but the gasket is used on early as well,anyway I have heard it said that these were the walmart big bore,but I aint racing so no diff.hahabillp

754 · « **Reply #11 on:** October 13, 2015, 06:00:11 PM »

Here is what your next set looks like, they are on the Way..
I figured you may like the box, so I built another to wrap around it.

BPellerine · « **Reply #12 on:** October 13, 2015, 06:05:31 PM »

thanks a lot frank,nice to have spares when you run obsolete stuff,and this proves that there are 3 diff kinds,those are like pewes,and flat.bill

PeWe · « **Reply #13 on:** October 14, 2015, 01:00:23 AM »

Quote from: Jerry Rxman Griffin aka MuthaF'er on October 13, 2015, 11:33:01 AM

My take is if the cylinders were made for the seals then use them.

As you say, there are 2 different HA 900 pistons. Maybe more?? I've only seen/noticed 2 types. You have the heavier ones.

It look like 2 versions of the older heavier ones. I have the older heavier but 67.5mm instead of 67.... measured with 2 different old Mitutoyo calipers with same result.
- Bill, can you measure your pistons, around skirts and top?

Bill/BentON Racing · « **Reply #14 on:** October 14, 2015, 05:05:37 AM »

My H Abe 900cc pistons, one might need some extra polishing!

, Bill

BPellerine · « **Reply #15 on:** October 14, 2015, 10:09:46 AM »

if you look closely at mine the valve cutouts are less half moon in shape,but the same dome.billp

PeWe · « **Reply #16 on:** October 14, 2015, 10:37:50 AM »

My HA pistons are very flat.

BPellerine · « **Reply #17 on:** October 14, 2015, 01:33:56 PM »

pewe I will measure mine for you,I will be getting a nos set like yours,I will be able to compare.wonder why the valve cutouts are like that?billp

BPellerine · « **Reply #18 on:** October 19, 2015, 08:02:51 PM »

I was wondering if anyone could tell me the effect on compression using these flat,67mm pistons with a stock combustion chamber would have,the slight dome is right at deck height.I know there are other factors that figure into this,but I have not milled the head or cyls at this point,just bigger bore into small chambers.thanks bill

BPellerine · « **Reply #19 on:** October 20, 2015, 10:55:04 AM »

Jerry Rxman Griffin aka MuthaF'er · « **Reply #20 on:** October 20, 2015, 12:09:59 PM »

Bill, here is the picture of my Henry Abe piston top. Looks like it was designed to be used without head chamber work maybe, which you had asked about in the PM?

turboguzzi · « **Reply #21 on:** October 20, 2015, 12:53:39 PM »

Quote from: Jerry Rxman Griffin aka MuthaF'er on October 20, 2015, 12:09:59 PM

Bill, here is the picture of my Henry Abe piston top. Looks like it was designed to be used without head chamber work maybe, which you had asked about in the PM?

can you put a side view of that 67mm piston? looks like the ticket for something i have in mind..... tnxs!

Jerry Rxman Griffin aka MuthaF'er · « **Reply #22 on:** October 20, 2015, 02:14:54 PM »

Unable to locate a clean picture at the moment

BPellerine · « **Reply #23 on:** October 20, 2015, 02:23:06 PM »

thanks jerry,I see yours are higher compression,with a 3mm band around the piston to clear head,the other one is really low compression!!!hahabollp

turboguzzi · « **Reply #24 on:** October 20, 2015, 10:56:24 PM »

Quote from: Jerry Rxman Griffin aka MuthaF'er on October 20, 2015, 02:14:54 PM

Unable to locate a clean picture at the moment

tnxs J. remember by any chance who high is the crown?

PeWe · « **Reply #25 on:** October 21, 2015, 02:57:40 AM »

Quote from: turboguzzi on October 20, 2015, 10:56:24 PM

Quote from: Jerry Rxman Griffin aka MuthaF'er on October 20, 2015, 02:14:54 PM
Unable to locate a clean picture at the moment

tnxs J. remember by any chance who high is the crown?

Sideview here? look like same model
http://forums.sohc4.net/index.php/topic,150456.msg1717048.html#msg1717048

Jerry Rxman Griffin aka MuthaF'er · « **Reply #26 on:** October 21, 2015, 09:26:25 AM »

Yes, that's it.

Don't have the dome height numbers.

PeWe · « **Reply #27 on:** October 21, 2015, 10:13:36 AM »

Or order and measure

http://www.ebay.com/itm/NOS-Honda-CB750-Henry-Abe-900CC-Big-Bore-Piston-Racing-Kit-CB-750-/301772834779

BPellerine · « **Reply #28 on:** October 21, 2015, 01:39:17 PM »

Quote from: PeWe on October 21, 2015, 10:13:36 AM

Or order and measure
http://www.ebay.com/itm/NOS-Honda-CB750-Henry-Abe-900CC-Big-Bore-Piston-Racing-Kit-CB-750-/301772834779

yikes!!big bucks!

BPellerine · « **Reply #29 on:** October 21, 2015, 01:49:08 PM »

so no one has any idea what compression ratio the ha stuff is,instructions say they increase comp so got to rejet?bill

turboguzzi · « **Reply #30 on:** October 21, 2015, 03:03:37 PM »

Quote from: BPellerine on October 21, 2015, 01:49:08 PM

so no one has any idea what compression ratio the ha stuff is,instructions say they increase comp so got to rejet?bill

just higher compression per se doesnt change flow characteristics, at least not much, shouldn't impact jetting (if it was good to begin with).
Did just a decking job on my xt600 supermoto, i.e. only compression was increased and at least in my case didnt need to touch jetting.
but if you are increasing displacement, not just compression, then flow speed through carbs will increase and jetting might have to change.

crazy price BTW, way out of my range....

BPellerine · « **Reply #31 on:** October 21, 2015, 05:24:21 PM »

thanks turboguzzi,I am going from 61mm bore to 67mm bore with the stock combustion chambers,my pistons are flat top,so was just trying to get an idea of the compression increase,ie bigger bore into small combustion chamber,stock comp is 9.1 or thereabouts.bill

NalleyRacing · « **Reply #32 on:** October 24, 2015, 06:33:53 PM »

So I have a NOS HA kit I plan to install over the winter. I also am removing a old set of HA pistons from a motor currently. These are the old and new for you to compare side by side. Definately interesting. Im going back In to check weight and size differences.

The flat style are stock compression the newer styler are 10.25:1

New kit appears to be lighter. With deep fly cuts.

scottly · « **Reply #33 on:** October 24, 2015, 08:02:37 PM »

Trey, slide a piston pin halfway through each piston to compare the compression heights.

BPellerine · « **Reply #34 on:** October 25, 2015, 04:35:00 PM »

yes trey that would be interesting to check height from pin,and yes your nos pistons are higher comp than mine,I was just trying to get an idea of what rise if any I would get/not get with the flat tops with std chambers ie bigger bore moving more air into them,it will not be much.bill

PeWe · « **Reply #35 on:** October 27, 2015, 02:55:50 PM »

Diameter of the older one?
Same as Bills or like mine that seems to be 0.5mm wider. 66.9mm at top, 67.45 around the skirt

BPellerine · « **Reply #36 on:** December 06, 2015, 01:34:48 PM »

here are my pistons installed!lightly ported ko head going on top!bill

Jerry Rxman Griffin aka MuthaF'er · « **Reply #37 on:** December 06, 2015, 04:56:39 PM »

Looks great Bill. It's downhill from here.

BPellerine · « **Reply #38 on:** December 07, 2015, 01:32:23 PM »

Quote from: Jerry Rxman Griffin aka MuthaF'er on December 06, 2015, 04:56:39 PM

Looks great Bill. It's downhill from here.

ya jerry that is what I am thinking too,always worked with twins,putting the barrels on a four is a whole ah hem,other experience !!done by spring!billp

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Author Topic: my henry abe pistons and cyls compression Q (Read 5306 times)